The present invention is directed to a vertical lathe apparatus, although certain features of the invention may have applicability in other areas, as may be evident to persons skilled in the art. In a vertical lathe, the work to be machined is mounted upon a turntable, which is rotatable about a vertical axis. The machine is provided with one (usually) or a plurality (occasionally) of rams adapted interchangeably to receive and support cutting tools appropriate to the required machining operations. The rams are mounted for controlled vertical movement in ram support housings, and these in turn are mounted for controlled horizontal movement on a cross slide carried by the machine frame. In some cases, provision may be made for a vertical adjustment of the cross slide itself, in addition to providing for vertical movement of the rams, in order to provide for optimum initial positioning of the rams with respect to a given work piece.
In the machining of a work piece on a vertical lathe apparatus, as generally described above, the work piece is fixed upon and rotated by the turntable and machining operations are performed by cutting tools carried by the rams. The desired cutting operations are performed by manipulating the position of the cutting tools, through vertical motions of the rams and horizontal movements of the ram supports. In a typical machining operation, carried out on vertical lathe equipment, a wide variety of cutting tools may be necessary or desirable for effecting various types of machining operations. Frequently, this has been accomplished in the past through the use of turrets mounted on the machine rams and selectively indexable to bring any one of several cutting tools into operative position. The turret arrangements are limited, however, by their tool holding capability in relation to size. Thus, as a practical matter, not more than four or five tools can be conveniently carried on a single turret, necessitating changing of entire turrets where (as is frequently the case) the typical production requirements of the machine involve the use of a greater number of tools. In addition, the use of tool-mounting turrets carried by the machine ram presents certain problems with respect to the accuracy of machining, because the geometry of the turret necessitates a mounting of the cutting tools somewhat more eccentrically, relative to the ram axis, than is desired. The use of the turrets also tends to limit, to a somewhat greater degree than desired, the minimum size of opening that the turret-carrying ram may enter to carry out internal machining.
An overall objective of the invention is to provide a vertical lathe machine of the type described with a novel and advantageous form of automatic tool change system, providing for a high speed, versatile changing of individual tools. Of course, the provision of automatic tool change facilities in machine tools of all kinds is well known, in the general sense, and the present invention does not purport to be directed broadly to the concept of automatic tool change. Rather, it is directed to the provision of an automatic tool change system, adapted particularly for vertical lathe equipment, which incorporates a number of novel and highly advantageous features providing for a high degree of efficiency and versatility in effecting the changing of tools in the course of production operations.
In accordance with one feature of the invention, a novel tool transport arrangement is provided for conveying a new cutting tool from a stationary tool matrix or "library" over to a ready-to-load position adjacent the ram, during the course of a machining operation with the previous tool. Thus, when the time comes for effecting a change of tools, it is merely necessary to retract the ram vertically from its extended machining position to a predetermined loading position and effect a rapid loading of the waiting new tool into the ram, in exchange for the previously used tool. In addition, a novel arrangement is provided for effecting a simultaneous exchange of tools in the ram with a linear "flow through" movement of tool blocks, minimizing the time required to effect the exchange of tools from the "ready" position.
In accordance with another feature of the invention, provision is made in the ram and in the tool library for receiving "right hand" and "left hand" tool blocks, for use in performing internal or external machining operations as may be required. In this respect, a "left hand" tool block desirably is mounted eccentrically to the left on the ram, while the "right hand" tool is mounted eccentrically to the right. To accommodate these possibilities, the tool transport system and the tool loading system incorporate selectively operable, automatic positioning means accommodating the various "left hand" and "right hand" tool blocks in their several (four) possible combinations. This arrangement permits the use of an advantageous highly simplified form of loading device having a pair of spaced tool engaging elements arranged simultaneously to engage the tool in use and the "ready" tool and with a controlled lateral movement slide the original tool out of position and the new tool into position with the proper right-side or left-side eccentricity. The apparatus of the invention also includes an improved carrousel-type system consituting a tool matrix or tool library for storing a plurality of tool blocks for eventual use. The general function of the carrousel is, of course, to bring the new tool blocks successively into position for transfer to the ram. In this respect, the equipment of the invention incorporates improved control facilities for reliably positioning the carrousel and for reliably retaining and releasing the various tool blocks as they are called for.